EVERETT, Wash. -- A 19-year-old Washington state man, who police say raped a high school student as she died from a drug overdose and texted semi-nude photos of her, has been charged with manslaughter.

Brian Roberto Varela of Lynnwood was also charged Friday in Snohomish County Superior Court with second-degree rape and controlled substance homicide in the death of 18-year-old Alyssa Mae Noceda.

According to court documents obtained by CBS affiliate KIRO, Varela told detectives they had done drugs together on Feb. 3 at a party at his Lynwood mobile home where he lives with a friend. Varela said Noceda snorted Percocet and also ingested liquid marijuana before collapsing in his room, the documents say.

Authorities say Varela never sought help for Noceda, instead sending semi-nude photos of her to friends and texting "LOL, I think she od'd, still breathing." In the photos, she was apparently unconscious, reports KIRO.

Varela allegedly said he was "too tired" to take her to the emergency room and went to bed, the station reports.

The next morning, after Noceda had died, he allegedly told detectives he used her thumb to unlock her phone and sent Snapchat messages to make it appear she had run away.

He then allegedly bragged to his co-workers at a Dairy Queen about sexually assaulting the girl as she died.

Authorities say his co-worker contacted police. According to the co-worker, Varela said he didn't know if Noceda was still alive when he was having sex with her. Court records say he told a friend that "she died having sex with me."

Police arrested Varela later that day after executing a search warrant and finding Noceda's body in a plastic crate at the suspect's home.

Varela told investigators he planned to bury Noceda with onions to minimize the odor, police said.

Friends of Noceda, a student at Mariner High School, held a vigil for her on Friday with more than a hundred people taking part, including her mother.

Noceda's mother Gina Pierson told KIRO that before the teen left home the night she died, she yelled to each of her family members by name and told them she loved them. Pierson said she had a strange feeling that something bad might happen, but she kept the thought to herself.